Hi!
Hmm, hacking around backup I have a question:
What prevents guest write request after job_start but before setting
write notifier?
code path:
qmp_drive_backup or transaction with backup
job_start
aio_co_enter(job_co_entry) /* may only schedule execution, isn't it ? */
....
job_co_entry
job_pause_point() /* it definitely yields, isn't it bad? */
job->driver->run() /* backup_run */
----
backup_run()
bdrv_add_before_write_notifier()
...
And what guarantees we give to the user? Is it guaranteed that write notifier is
set when qmp command returns?
And I guess, if we start several backups in a transaction it should be
guaranteed
that the set of backups is consistent and correspond to one point in time...
--
Best regards,
Vladimir
